This invention relates to an apparatus and method for testing or determining the amount of force required to bend a sheet of material, such as corrugated board, along a score line.
In the manufacture of material such as corrugated board or paperboard, it is common to provide scores or other demarcations at locations where a blank is to be folded. Such scores or demarcations can provide varying degrees of ease of folding of the blank, and it is desirable to know the amount of force required to bend the blank at the score. This is especially the case when the bend or fold is to be made using automated equipment.
It is an object of the present invention to provide an apparatus and method for testing the amount of force required to bend a sheet of material such as corrugated board or paperboard along a score or other demarcation. It is a further object of the invention to provide an apparatus which is relatively simple in its construction and operation, yet which is capable of providing a high degree of accuracy in determining the amount of force required to bend the sheet of material at the score. Yet another object of the invention is to provide a method which is easily and simply carried out using a relatively small number of steps. A still further object of the invention is to provide a quick and easy score bend or folding test which can be quickly repeated by an operator in a safe and efficient manner.
In accordance with the invention, a score bend testing apparatus includes a base having an upwardly facing planar support surface defining a forward edge, and a clamp for clamping the sheet of material, such as corrugated board or paperboard, against the support surface such that the score is located outwardly or forwardly of the edge. A force applying arrangement applies a downward force to the sheet of material outwardly or forwardly of the score, and continues application of the downward force until the sheet of material bends at the score. A force measuring arrangement is interconnected with the force applying arrangement for determining the amount of force required to bend the sheet at the score. The upwardly facing planar surface of the base is oriented at an angle to horizontal, such that the portions of the base rearwardly of the forward edge slope downwardly. The base includes an upstanding member associated with its rear portion, which is adapted to engage a rear edge defined by the sheet of material to position the sheet of material relative to the forward edge of the base. The clamp is preferably mounted to the upstanding member, and includes an extendable and retractable member for selectively engaging the sheet of material to clamp it against the base. The force applying arrangement includes a pair of spaced supports located one on either side of the base, with the sheet of material being disposed between the spaced supports. An operating device, such as a pneumatic cylinder assembly, is mounted to each support. Each operating device includes an output member which is selectively movable in an upward and downward direction. A cross-member extends between and is interconnected with the output members for selective upward and downward movement therewith. An engagement member is mounted to the cross-member for engaging the sheet of material upon downward movement of the cross-member. The engagement member is preferably a rod-like member which extends along an axis parallel to the forward edge of the base and to the score. The cross-member is disposed forwardly of the base forward edge, and extends parallel relative thereto. The force measuring arrangement is mounted to the cross-member and, in a preferred embodiment, the force applying arrangement and force measuring arrangement are in the form of an integral force gauge unit secured to the cross-member.
The invention also contemplates a method of determining the amount of force required to bend a sheet of material at a longitudinal score, substantially in accordance with the foregoing summary.